502 LACERTILIA CHAP. 



Mediterranean countries. This is very puzzling, considering that 

 these subterranean, helpless creatures positively cannot travel. 

 Boulenger regards them " as a degraded type of the Tejidae, with 

 which they are to some extent connected by Chalcides and its 

 allies," i.e. genera with reduced limbs, cf. p. 562. 



However, this supposed relationship with a strictly American 

 family does not explain the occurrence of Amphisbaenidae in 

 Africa. Either they are not a natural group, or they had, 

 as already degraded, limbless creatures, a much wider range ; and 

 this would imply their being a very old family, perhaps as old as 

 we suppose the Coecilians to be. 



Anguidae occur in North and South America, in Europe and 

 the Mediterranean parts of North Africa, and in Trans- 

 G-angetic India. Their older relations, the Zonuridae, inhabit 

 Africa and Madagascar. 



Madagascar is consequently devoid of Agamidae, Varanidae, 

 Lacertidae, Anguidae, and Amphisbaenidae, while it possesses, 

 besides the cosmopolitan Scincidae and Geckones, only Chameleons, 

 Gerrhosauridae, and Zonuridae, all three essentially African 

 families, and a few Iguanidae. This means that the Autosaurian 

 fauna of Madagascar is intimately related to that of Africa, and 

 that it possesses only old families so far as Sauria are concerned. 

 But since this great island was separated from its continent not 

 earlier than in Mid-Tertiary times, it follows that most of these 

 " old " families are comparatively recent. 



Australia possesses only Agamidae and Varanidae besides the 

 ubiquitous Geckos and Skinks. Besides the latter two families it 

 has nothing in common either with Madagascar (an analogy with 

 the Anura) or with America. The Autosauri consequently do not 

 support the idea of a Notogaea, cf. p. 74. This again indicates 

 the comparatively recent age of Autosaurian families. The 

 marked difference which exists between the Old and the New 

 World points to the same conclusion. On the other . hand, the 

 Autosauri support the idea that the Palaeotropical region is but 

 the tropical and therefore richer continuation of the now 

 impoverished Palaearctic sub-region. 



Sub -Order 1. Geckones. The typical Geckos are char- 

 acterised as follows. Four-footed Autosauri with amphicoelous 

 vertebrae; skull ivithout bony temporal arches; clavicles dilated 

 and with a perforation near the ventral end; parietal bones 



